We are using Extended Cross-Correlation (XCC) to identify which chemicals are present in breast tissue and are correlated with precancerous changes. XCC is a pattern recognition technique that was recently developed to enable spectroscopists to identify peaks corresponding to the same chemical in a mixture of chemicals. It is especially suited for extracting those chemicals that are present in a mixture when the signals are both complex and initially unknown. Thus, this technique will enable us to characterize the different chemicals that are normally found in breast tissue. Once we know which chemicals are present, we can then correlate chemical concentrations with pathology. Finally, with this knowledge we can then develop a suitable algorithm for diagnosing breast cancer based on Raman spectra.